I'm a maths major and I have an interest in learning biology. I know very, very little; I know how babies are made and that's about it. Could anyone recommend a stimulating text to read for its own sake and also to use to learn biology?
I found the Campbell Biology textbook to be quite comprehensive and approachable. I think many introductory biology courses use it.
There are tons of books and it is quite hard to find one that gives such a broad overview. Campbell Biology is a book that basically covered the first year of my Bachelor degree in biology. I am not sure it would be very stimulating though! If there is a specific branch of biology that interests you, let us know we'll be able to give you a better advice.
As a math Major you might enjoy some fields of biology that are highly mathematized. For example, system biology or theoretical evolutionary biology. For the latter, you might like to read Evolutionary Dynamics: Exploring the Equations of Life book from Martin Nowak. But I am afraid it might not be a nice idea to directly jump into some specific subject before having a good overview of the life sciences.
Otherwise you might appreciate some books of popular (but good level) science such as the Extended Phenotype from Richard Dawkins. This book is very stimulating and I think it starts with some basic definitions of biological concepts such those of "alleles" or "phenotype".
I gave you two examples of books from the field of theoretical evolutionary biology. For more recommendations in this field, please have a look at Books on population or evolutionary genetics?.
Hope this helps a bit!
You should check out Richard Dawkins' book The Greatest Show on Earth: The Evidence for Evolution
It does focus heavily on evolution but it is an amazing book on biology in general. He covers a wide rage of other topics, from how birds flock so elegantly to dating fossils using dendrochronology. The chapter on embryology is fascinating.
@xuanji offers a good choice with Campbell Biology if you want a text solid biology textbook. I've got a copy in my library. I would suggest buying a previous edition if you're trying to save money. However, the book could be a bit dry. Reading semi-popular books on topics you are interested about would probably be better approach.
Both @ebrohman and @Remi.b provide good suggestions with Dawkins. I also like Ernst Mayr's What is evolution on the topic of evolution.
If you want to learn more about environmental toxicology, Rachel Carson's Silent Spring is a good book to start off with.
If you're looking for a mathematical biology book, Linda Allen has two biomath text books, one on deterministic models the other on stochastic models. Murry's also produced some classical mathematical biology books. Most people would consider these books dry, but as a mathematician, you might like them.
James Watson can be controversial but he's written some interesting books. His Double Helix is a good read.
If you provide what specific type of biology and mathematics you are interested in, I will provide more suggestions.
The Bible of biology is the Alberts' Molecular Biology of the Cell:
The Campbell is also pretty good and maybe easier to read..